Homocysteine in Plasma

Intermediate of methionine metabolism whose blood level reflects folate, vitamin B12, and vitamin B6 availability, kidney clearance, and genetics such as MTHFR variants.
Also known as:
P-homocysteine
HCY
P-HCY
HCYST
.

Homocysteine ranges

Interpret your result
"Normal" lab range for Homocysteine is between 5 and 15 µmol/L:
5
15
According to Peter Attia, Homocysteine should be below 9 µmol/L:
9
According to OptimalDX, Homocysteine should be between 5 and 7.2 µmol/L:
5
7.2
B12 deficiency was associated with Homocysteine above 15 µmol/L:
15
Optimal range
Optimal range for Homocysteine appears to be between 5 and 8 µmol/L:
2
5
8
12
25
Why this optimal range?
Preliminary range is based on functional health organizations including but not limited to those listed above.

What a low value may mean:

Common reasons for low Homocysteine:

  • homocysteine is a substrate for glutathione and cysteine synthesis, very low levels may limit these antioxidant and detoxification pathways. Low levels have also been associated with idiopathic peripheral neuropathy.

    ,

What a high value may mean:

Common reasons for high Homocysteine:

  • High homocysteine most often reflects insufficient folate, vitamin B12, or vitamin B6 — the main and usually correctable cause, including with vegetarian or vegan diets (lower B12).

    Other contributors: impaired kidney function (reduced clearance), hypothyroidism, MTHFR and related genetic variants (MTR, CBS), advancing age, smoking, alcohol, chronic stress, and certain medications (methotrexate, metformin, cholestyramine, antiepileptics). Markedly high levels suggest inherited homocystinuria.

    ,

Possible consequences from high Homocysteine:

  • Cardiovascular disease (Atherosclerosis, Heart attack, Stroke)
  • Neurodegenerative disorders (Alzheimer's, Parkinson's, Dementia),

How to lower Homocysteine:

  • B12, folate and vitamin B6 supplementation
    Consider the methylated versions of B12 and folate (methylcobalamin and methylfolate)

Images:

Homocysteine increases during aging

Homocysteine increases during aging

High Homocysteine was associated with substantial rise in all-cause mortality

High Homocysteine was associated with substantial rise in all-cause mortality

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Zsolt Szabo
Zsolt Szabo
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I am particularly interested in research on biomarkers associated with all-cause mortality and on defining optimal reference ranges.